Because of various governmental regulations relating to vehicular engine exhaust emissions, it has been found necessary to supply additional quantities of oxygen, as by atmospheric air, to the engine exhaust gases, prior to such gases being discharged into the atmosphere, in order to further burn (oxidize) such gases and thereby reduce the quantity of unburned hydrocarbons emitted into the atmosphere.
Heretofore, the prior art has proposed the employment of various valving means for directing such additional quantities of air (supplied as by related air pumping means) to the engine exhaust system. However, it has been discovered that such prior art means and devices are not entirely satisfactory in that they are often non-responsive (or responsive but less than desired) to certain conditions or parameters of engine operation thereby resulting, for example, in such additional air being supplied to the exhaust system at times when such additional air is not actually desired.
The invention as herein disclosed and claimed is primarily directed to the solution of such problems of the prior art as well as other related and attendant problems.